Fluoride electrode with LaF3-membrane and simple disjoining solid-state internal contact

Fluoride-selective electrode with LaF3-membrane and stainless steel interna l contact has been prepared. The electrode has been tested in F- concentrat ion range 10(-2)-10(-6) M and the results compared with those of commercial electrode and electrode with laboratory renewed internal electrolytic cont act. The properties of simple disjoining solid-state contact have been inve stigated by means of electrochemical impedance spectroscopy (EIS). The impe dance spectra show two time constants, which suggest that, at lower frequen cies, proceed some Faradic reaction which probably stabilizes the potential between LaF3-membrane and stainless steel disk. (C) 2001 Elsevier Science B.V. All rights reserved.